Developer units, also known as customer replaceable units or "CRU's", are known. Typically, developer units are arranged for mounting in a host printing machine to develop a latent image present on a photosensitive member. A typical developer unit comprises a donor roll (also known as a "mag roll") and contains a supply of developer compound, also known as "toner". The developer unit is arranged for supplying developer compound to the donor roll. The donor roll, in turn, is arranged to provide developer compound to the photosensitive member. Ultimately, the host printing machine produces copies of the developed latent image.
It is desirable for a developer unit to be capable of producing a large number of copies before its supply of developer compound becomes exhausted. As a result, it is thus advantageous for a developer unit to be capable of storing a large quantity of developer compound.
Once a developer unit's supply of developer compound is exhausted, the developer unit must be refilled or replenished with additional developer compound. Some developer units include a replenish port for purposes of replenishing by the user. With this arrangement, the user adds developer compound to the replenish port in order to replenish the developer unit with additional developer compound.
Typical developer units comprise internal agitators arranged to push or propel the developer compound to the donor roll. In large-capacity developer units, typically two (2) or more agitators are used in tandem. With a two-agitator developer unit design, for example, a first agitator is arranged for propelling developer compound to a second agitator. The second agitator, in turn, is arranged for propelling developer compound to the donor roll.
It is known that the developer unit business (industry) is very competitive. To gain competitive advantage, therefore, it is desirable to minimize the unit manufacturing cost of a developer unit. A developer unit's manufacturing cost is based on many cost factors, one key cost factor being the total number of components comprised by the developer unit. As a result, reducing the developer unit's total component count generally also will reduce the developer unit's manufacturing cost.
One cost limitation of a developer unit comprising multiple agitators, therefore, is the cost of the multiple agitator components. Thus, it would be desirable to provide a replenishable developer unit with one (1) agitator.
The problem, therefore, is how to reduce the number of agitators required in a replenishable developer unit, hopefully to a single (1) agitator.
As a result, there is a need for an improved replenishable developer unit.